連鑄坯中心質(zhì)量對(duì)無(wú)縫鋼管內(nèi)折的影響
Influence by CC Billet Central Quality on Internal Fold of Seamless Steel Tube
-
摘要: 無(wú)縫鋼管內(nèi)折的表現(xiàn)形式多種多樣,產(chǎn)生原因比較復(fù)雜。通過(guò)對(duì)鑄坯、無(wú)縫鋼管、軋鋼事故管坯進(jìn)行酸浸低倍檢驗(yàn),研究了連鑄圓坯心部質(zhì)量與內(nèi)折缺陷形式的對(duì)應(yīng)關(guān)系,發(fā)現(xiàn)具有發(fā)達(dá)的樹枝晶的鑄坯心部容易產(chǎn)生中心裂紋,它所形成的無(wú)縫鋼管內(nèi)折的形式為向內(nèi)延伸的沿晶裂紋;中心疏松嚴(yán)重的鑄坯心部容易產(chǎn)生點(diǎn)狀和發(fā)紋狀間隙,它所形成的無(wú)縫鋼管內(nèi)折的形式為平行于內(nèi)表面的層狀裂紋。在工藝方面,采用結(jié)晶器電磁攪拌(M-EMS)技術(shù)后使鑄坯的中心等軸晶區(qū)擴(kuò)大,20鋼鋼管內(nèi)折率從0.22%下降到0.07%。Abstract: Internal folds of seamless steel pipes fall into various types due to rather complicated causes for such defect. CC round central quality vs the fold type is studied with acid etch macrostructure tests as conducted to CC billet,seamless steel pipe and the shell from some rolling failure. As a result,it is identified that billet center with rich dendrites is apt to produce central cracks which lead to pipe internal folds featuring cracks running inward along with the dendrites,while billet center with serious porosity is apt to develop spotted and hair-lined clearances which lead to pipe internal folds as laminal cracks parallel to the inner surface. Accordingly, the mould-electric magnetic stirring (M-EMS) process is used to enlarge the billet central equiaxed zone,having got the internal fold rate of the 20 pipe reduced from the original 0.22% to 0.07%.
下載: